forked from M-Labs/nac3
1098 lines
42 KiB
Rust
1098 lines
42 KiB
Rust
use itertools::{chain, zip, Itertools};
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use std::borrow::Cow;
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use std::cell::RefCell;
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use std::collections::HashMap;
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use std::iter::once;
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use std::rc::Rc;
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use std::sync::{Arc, Mutex};
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use rustpython_parser::ast::StrRef;
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use super::unification_table::{UnificationKey, UnificationTable};
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use crate::symbol_resolver::SymbolValue;
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use crate::toplevel::{DefinitionId, TopLevelContext, TopLevelDef};
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#[cfg(test)]
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mod test;
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/// Handle for a type, implementated as a key in the unification table.
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pub type Type = UnificationKey;
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#[derive(Clone, Copy, PartialEq, Eq, Debug)]
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pub struct CallId(usize);
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pub type Mapping<K, V = Type> = HashMap<K, V>;
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type VarMap = Mapping<u32>;
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#[derive(Clone)]
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pub struct Call {
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pub posargs: Vec<Type>,
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pub kwargs: HashMap<StrRef, Type>,
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pub ret: Type,
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pub fun: RefCell<Option<Type>>,
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}
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#[derive(Clone)]
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pub struct FuncArg {
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pub name: StrRef,
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pub ty: Type,
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pub default_value: Option<SymbolValue>,
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}
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#[derive(Clone)]
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pub struct FunSignature {
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pub args: Vec<FuncArg>,
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pub ret: Type,
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pub vars: VarMap,
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}
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#[derive(Clone)]
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pub enum TypeVarMeta {
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Generic,
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Sequence(RefCell<Mapping<i32>>),
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Record(RefCell<Mapping<StrRef>>),
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}
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#[derive(Clone)]
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pub enum TypeEnum {
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TRigidVar {
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id: u32,
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},
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TVar {
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id: u32,
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meta: TypeVarMeta,
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// empty indicates no restriction
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range: RefCell<Vec<Type>>,
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},
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TTuple {
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ty: Vec<Type>,
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},
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TList {
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ty: Type,
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},
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TObj {
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obj_id: DefinitionId,
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fields: RefCell<Mapping<StrRef>>,
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params: RefCell<VarMap>,
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},
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TVirtual {
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ty: Type,
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},
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TCall(RefCell<Vec<CallId>>),
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TFunc(RefCell<FunSignature>),
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}
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impl TypeEnum {
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pub fn get_type_name(&self) -> &'static str {
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match self {
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TypeEnum::TRigidVar { .. } => "TRigidVar",
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TypeEnum::TVar { .. } => "TVar",
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TypeEnum::TTuple { .. } => "TTuple",
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TypeEnum::TList { .. } => "TList",
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TypeEnum::TObj { .. } => "TObj",
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TypeEnum::TVirtual { .. } => "TVirtual",
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TypeEnum::TCall { .. } => "TCall",
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TypeEnum::TFunc { .. } => "TFunc",
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}
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}
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}
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pub type SharedUnifier = Arc<Mutex<(UnificationTable<TypeEnum>, u32, Vec<Call>)>>;
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#[derive(Clone)]
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pub struct Unifier {
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pub top_level: Option<Arc<TopLevelContext>>,
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unification_table: UnificationTable<Rc<TypeEnum>>,
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calls: Vec<Rc<Call>>,
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var_id: u32,
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}
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impl Unifier {
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/// Get an empty unifier
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pub fn new() -> Unifier {
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Unifier {
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unification_table: UnificationTable::new(),
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var_id: 0,
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calls: Vec::new(),
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top_level: None,
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}
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}
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// copy concrete type from a type in another unifier
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// note that we are constructing a new type this way
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// this can handle recursive types
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pub fn copy_from(
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&mut self,
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unifier: &mut Unifier,
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ty: Type,
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type_cache: &mut HashMap<Type, Type>,
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) -> Type {
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let representative = unifier.get_representative(ty);
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type_cache.get(&representative).cloned().unwrap_or_else(|| {
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// put in a placeholder first to handle possible recursive type
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let placeholder = self.get_fresh_var().0;
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type_cache.insert(representative, placeholder);
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let ty = match &*self.get_ty(ty) {
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TypeEnum::TVar { .. } | TypeEnum::TRigidVar { .. } | TypeEnum::TCall(..) => {
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unreachable!()
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}
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TypeEnum::TObj { obj_id, fields, params } => TypeEnum::TObj {
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obj_id: *obj_id,
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fields: RefCell::new(
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fields
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.borrow()
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.iter()
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.map(|(name, ty)| {
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(*name, self.copy_from(unifier, *ty, type_cache))
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})
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.collect(),
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),
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params: RefCell::new(
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params
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.borrow()
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.iter()
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.map(|(id, ty)| (*id, self.copy_from(unifier, *ty, type_cache)))
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.collect(),
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),
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},
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TypeEnum::TList { ty } => {
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TypeEnum::TList { ty: self.copy_from(unifier, *ty, type_cache) }
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}
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TypeEnum::TFunc(fun) => {
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let fun = fun.borrow();
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TypeEnum::TFunc(RefCell::new(FunSignature {
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args: fun
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.args
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.iter()
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.map(|arg| FuncArg {
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name: arg.name,
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ty: self.copy_from(unifier, arg.ty, type_cache),
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default_value: arg.default_value.clone(),
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})
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.collect(),
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ret: self.copy_from(unifier, fun.ret, type_cache),
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vars: fun
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.vars
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.iter()
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.map(|(id, ty)| (*id, self.copy_from(unifier, *ty, type_cache)))
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.collect(),
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}))
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}
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TypeEnum::TTuple { ty } => TypeEnum::TTuple {
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ty: ty.iter().map(|ty| self.copy_from(unifier, *ty, type_cache)).collect(),
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},
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TypeEnum::TVirtual { ty } => {
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TypeEnum::TVirtual { ty: self.copy_from(unifier, *ty, type_cache) }
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}
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};
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let ty = self.add_ty(ty);
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self.unify(placeholder, ty).unwrap();
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type_cache.insert(representative, ty);
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ty
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})
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}
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/// Determine if the two types are the same
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pub fn unioned(&mut self, a: Type, b: Type) -> bool {
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self.unification_table.unioned(a, b)
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}
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pub fn from_shared_unifier(unifier: &SharedUnifier) -> Unifier {
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let lock = unifier.lock().unwrap();
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Unifier {
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unification_table: UnificationTable::from_send(&lock.0),
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var_id: lock.1,
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calls: lock.2.iter().map(|v| Rc::new(v.clone())).collect_vec(),
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top_level: None,
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}
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}
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pub fn get_shared_unifier(&self) -> SharedUnifier {
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Arc::new(Mutex::new((
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self.unification_table.get_send(),
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self.var_id,
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self.calls.iter().map(|v| v.as_ref().clone()).collect_vec(),
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)))
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}
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/// Register a type to the unifier.
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/// Returns a key in the unification_table.
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pub fn add_ty(&mut self, a: TypeEnum) -> Type {
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self.unification_table.new_key(Rc::new(a))
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}
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pub fn add_record(&mut self, fields: Mapping<StrRef>) -> Type {
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let id = self.var_id + 1;
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self.var_id += 1;
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self.add_ty(TypeEnum::TVar {
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id,
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range: vec![].into(),
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meta: TypeVarMeta::Record(fields.into()),
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})
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}
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pub fn add_call(&mut self, call: Call) -> CallId {
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let id = CallId(self.calls.len());
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self.calls.push(Rc::new(call));
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id
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}
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pub fn get_call_signature(&mut self, id: CallId) -> Option<FunSignature> {
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let fun = self.calls.get(id.0).unwrap().fun.borrow().unwrap();
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if let TypeEnum::TFunc(sign) = &*self.get_ty(fun) {
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Some(sign.borrow().clone())
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} else {
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None
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}
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}
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pub fn get_representative(&mut self, ty: Type) -> Type {
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self.unification_table.get_representative(ty)
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}
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pub fn add_sequence(&mut self, sequence: Mapping<i32>) -> Type {
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let id = self.var_id + 1;
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self.var_id += 1;
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self.add_ty(TypeEnum::TVar {
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id,
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range: vec![].into(),
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meta: TypeVarMeta::Sequence(sequence.into()),
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})
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}
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/// Get the TypeEnum of a type.
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pub fn get_ty(&mut self, a: Type) -> Rc<TypeEnum> {
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self.unification_table.probe_value(a).clone()
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}
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pub fn get_fresh_rigid_var(&mut self) -> (Type, u32) {
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let id = self.var_id + 1;
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self.var_id += 1;
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(self.add_ty(TypeEnum::TRigidVar { id }), id)
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}
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pub fn get_fresh_var(&mut self) -> (Type, u32) {
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self.get_fresh_var_with_range(&[])
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}
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/// Get a fresh type variable.
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pub fn get_fresh_var_with_range(&mut self, range: &[Type]) -> (Type, u32) {
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let id = self.var_id + 1;
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self.var_id += 1;
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let range = range.to_vec().into();
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(self.add_ty(TypeEnum::TVar { id, range, meta: TypeVarMeta::Generic }), id)
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}
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/// Unification would not unify rigid variables with other types, but we want to do this for
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/// function instantiations, so we make it explicit.
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pub fn replace_rigid_var(&mut self, rigid: Type, b: Type) {
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assert!(matches!(&*self.get_ty(rigid), TypeEnum::TRigidVar { .. }));
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self.set_a_to_b(rigid, b);
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}
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pub fn get_instantiations(&mut self, ty: Type) -> Option<Vec<Type>> {
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match &*self.get_ty(ty) {
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TypeEnum::TVar { range, .. } => {
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let range = range.borrow();
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if range.is_empty() {
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None
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} else {
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Some(
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range
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.iter()
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.map(|ty| self.get_instantiations(*ty).unwrap_or_else(|| vec![*ty]))
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.flatten()
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.collect_vec(),
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)
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}
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}
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TypeEnum::TList { ty } => self
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.get_instantiations(*ty)
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.map(|ty| ty.iter().map(|&ty| self.add_ty(TypeEnum::TList { ty })).collect_vec()),
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TypeEnum::TVirtual { ty } => self.get_instantiations(*ty).map(|ty| {
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ty.iter().map(|&ty| self.add_ty(TypeEnum::TVirtual { ty })).collect_vec()
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}),
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TypeEnum::TTuple { ty } => {
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let tuples = ty
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.iter()
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.map(|ty| self.get_instantiations(*ty).unwrap_or_else(|| vec![*ty]))
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.multi_cartesian_product()
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.collect_vec();
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if tuples.len() == 1 {
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None
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} else {
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Some(
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tuples.into_iter().map(|ty| self.add_ty(TypeEnum::TTuple { ty })).collect(),
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)
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}
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}
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TypeEnum::TObj { params, .. } => {
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let params = params.borrow();
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let (keys, params): (Vec<&u32>, Vec<&Type>) = params.iter().unzip();
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let params = params
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.into_iter()
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.map(|ty| self.get_instantiations(*ty).unwrap_or_else(|| vec![*ty]))
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.multi_cartesian_product()
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.collect_vec();
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if params.len() <= 1 {
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None
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} else {
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Some(
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params
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.into_iter()
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.map(|params| {
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self.subst(
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ty,
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&zip(keys.iter().cloned().cloned(), params.iter().cloned())
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.collect(),
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)
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.unwrap_or(ty)
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})
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.collect(),
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)
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}
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}
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_ => None,
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}
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}
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pub fn is_concrete(&mut self, a: Type, allowed_typevars: &[Type]) -> bool {
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use TypeEnum::*;
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match &*self.get_ty(a) {
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TRigidVar { .. } => true,
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TVar { .. } => allowed_typevars.iter().any(|b| self.unification_table.unioned(a, *b)),
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TCall { .. } => false,
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TList { ty } => self.is_concrete(*ty, allowed_typevars),
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TTuple { ty } => ty.iter().all(|ty| self.is_concrete(*ty, allowed_typevars)),
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TObj { params: vars, .. } => {
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vars.borrow().values().all(|ty| self.is_concrete(*ty, allowed_typevars))
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}
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// functions are instantiated for each call sites, so the function type can contain
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// type variables.
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TFunc { .. } => true,
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TVirtual { ty } => self.is_concrete(*ty, allowed_typevars),
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}
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}
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pub fn unify(&mut self, a: Type, b: Type) -> Result<(), String> {
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if self.unification_table.unioned(a, b) {
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Ok(())
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} else {
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self.unify_impl(a, b, false)
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}
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}
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fn unify_impl(&mut self, a: Type, b: Type, swapped: bool) -> Result<(), String> {
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use TypeEnum::*;
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use TypeVarMeta::*;
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let (ty_a, ty_b) = {
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(
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self.unification_table.probe_value(a).clone(),
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self.unification_table.probe_value(b).clone(),
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)
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};
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match (&*ty_a, &*ty_b) {
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(TVar { meta: meta1, range: range1, .. }, TVar { meta: meta2, range: range2, .. }) => {
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self.occur_check(a, b)?;
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self.occur_check(b, a)?;
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match (meta1, meta2) {
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(Generic, _) => {}
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(_, Generic) => {
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return self.unify_impl(b, a, true);
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}
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(Record(fields1), Record(fields2)) => {
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let mut fields2 = fields2.borrow_mut();
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for (key, value) in fields1.borrow().iter() {
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if let Some(ty) = fields2.get(key) {
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self.unify(*ty, *value)?;
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} else {
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fields2.insert(key.clone(), *value);
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}
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}
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}
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(Sequence(map1), Sequence(map2)) => {
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let mut map2 = map2.borrow_mut();
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for (key, value) in map1.borrow().iter() {
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if let Some(ty) = map2.get(key) {
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self.unify(*ty, *value)?;
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} else {
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map2.insert(*key, *value);
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}
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}
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}
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_ => {
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return Err("Incompatible type variables".to_string());
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}
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}
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let range1 = range1.borrow();
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// new range is the intersection of them
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// empty range indicates no constraint
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if !range1.is_empty() {
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let old_range2 = range2.take();
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let mut range2 = range2.borrow_mut();
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if old_range2.is_empty() {
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range2.extend_from_slice(&range1);
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}
|
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for v1 in old_range2.iter() {
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for v2 in range1.iter() {
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if let Ok(result) = self.get_intersection(*v1, *v2) {
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range2.push(result.unwrap_or(*v2));
|
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}
|
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}
|
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}
|
|
if range2.is_empty() {
|
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return Err(
|
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"cannot unify type variables with incompatible value range".to_string()
|
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);
|
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}
|
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}
|
|
self.set_a_to_b(a, b);
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}
|
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(TVar { meta: Generic, id, range, .. }, _) => {
|
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self.occur_check(a, b)?;
|
|
// We check for the range of the type variable to see if unification is allowed.
|
|
// Note that although b may be compatible with a, we may have to constrain type
|
|
// variables in b to make sure that instantiations of b would always be compatible
|
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// with a.
|
|
// The return value x of check_var_compatibility would be a new type that is
|
|
// guaranteed to be compatible with a under all possible instantiations. So we
|
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// unify x with b to recursively apply the constrains, and then set a to x.
|
|
let x = self.check_var_compatibility(*id, b, &range.borrow())?.unwrap_or(b);
|
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self.unify(x, b)?;
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self.set_a_to_b(a, x);
|
|
}
|
|
(TVar { meta: Sequence(map), id, range, .. }, TTuple { ty }) => {
|
|
self.occur_check(a, b)?;
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|
let len = ty.len() as i32;
|
|
for (k, v) in map.borrow().iter() {
|
|
// handle negative index
|
|
let ind = if *k < 0 { len + *k } else { *k };
|
|
if ind >= len || ind < 0 {
|
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return Err(format!(
|
|
"Tuple index out of range. (Length: {}, Index: {})",
|
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len, k
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));
|
|
}
|
|
self.unify(*v, ty[ind as usize])?;
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}
|
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let x = self.check_var_compatibility(*id, b, &range.borrow())?.unwrap_or(b);
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self.unify(x, b)?;
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self.set_a_to_b(a, x);
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}
|
|
(TVar { meta: Sequence(map), id, range, .. }, TList { ty }) => {
|
|
self.occur_check(a, b)?;
|
|
for v in map.borrow().values() {
|
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self.unify(*v, *ty)?;
|
|
}
|
|
let x = self.check_var_compatibility(*id, b, &range.borrow())?.unwrap_or(b);
|
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self.unify(x, b)?;
|
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self.set_a_to_b(a, x);
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}
|
|
(TTuple { ty: ty1 }, TTuple { ty: ty2 }) => {
|
|
if ty1.len() != ty2.len() {
|
|
return Err(format!(
|
|
"Cannot unify tuples with length {} and {}",
|
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ty1.len(),
|
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ty2.len()
|
|
));
|
|
}
|
|
for (x, y) in ty1.iter().zip(ty2.iter()) {
|
|
self.unify(*x, *y)?;
|
|
}
|
|
self.set_a_to_b(a, b);
|
|
}
|
|
(TList { ty: ty1 }, TList { ty: ty2 }) => {
|
|
self.unify(*ty1, *ty2)?;
|
|
self.set_a_to_b(a, b);
|
|
}
|
|
(TVar { meta: Record(map), id, range, .. }, TObj { fields, .. }) => {
|
|
self.occur_check(a, b)?;
|
|
for (k, v) in map.borrow().iter() {
|
|
let ty = fields
|
|
.borrow()
|
|
.get(k)
|
|
.copied()
|
|
.ok_or_else(|| format!("No such attribute {}", k))?;
|
|
self.unify(ty, *v)?;
|
|
}
|
|
let x = self.check_var_compatibility(*id, b, &range.borrow())?.unwrap_or(b);
|
|
self.unify(x, b)?;
|
|
self.set_a_to_b(a, x);
|
|
}
|
|
(TVar { meta: Record(map), id, range, .. }, TVirtual { ty }) => {
|
|
self.occur_check(a, b)?;
|
|
let ty = self.get_ty(*ty);
|
|
if let TObj { fields, .. } = ty.as_ref() {
|
|
for (k, v) in map.borrow().iter() {
|
|
let ty = fields
|
|
.borrow()
|
|
.get(k)
|
|
.copied()
|
|
.ok_or_else(|| format!("No such attribute {}", k))?;
|
|
if !matches!(self.get_ty(ty).as_ref(), TFunc { .. }) {
|
|
return Err(format!("Cannot access field {} for virtual type", k));
|
|
}
|
|
self.unify(*v, ty)?;
|
|
}
|
|
} else {
|
|
// require annotation...
|
|
return Err("Requires type annotation for virtual".to_string());
|
|
}
|
|
let x = self.check_var_compatibility(*id, b, &range.borrow())?.unwrap_or(b);
|
|
self.unify(x, b)?;
|
|
self.set_a_to_b(a, x);
|
|
}
|
|
(
|
|
TObj { obj_id: id1, params: params1, .. },
|
|
TObj { obj_id: id2, params: params2, .. },
|
|
) => {
|
|
if id1 != id2 {
|
|
self.incompatible_types(a, b)?;
|
|
}
|
|
for (x, y) in zip(params1.borrow().values(), params2.borrow().values()) {
|
|
self.unify(*x, *y)?;
|
|
}
|
|
self.set_a_to_b(a, b);
|
|
}
|
|
(TVirtual { ty: ty1 }, TVirtual { ty: ty2 }) => {
|
|
self.unify(*ty1, *ty2)?;
|
|
self.set_a_to_b(a, b);
|
|
}
|
|
(TCall(calls1), TCall(calls2)) => {
|
|
// we do not unify individual calls, instead we defer until the unification wtih a
|
|
// function definition.
|
|
calls2.borrow_mut().extend_from_slice(&calls1.borrow());
|
|
}
|
|
(TCall(calls), TFunc(signature)) => {
|
|
self.occur_check(a, b)?;
|
|
let required: Vec<StrRef> = signature
|
|
.borrow()
|
|
.args
|
|
.iter()
|
|
.filter(|v| v.default_value.is_none())
|
|
.map(|v| v.name)
|
|
.rev()
|
|
.collect();
|
|
// we unify every calls to the function signature.
|
|
for c in calls.borrow().iter() {
|
|
let Call { posargs, kwargs, ret, fun } = &*self.calls[c.0].clone();
|
|
let instantiated = self.instantiate_fun(b, &*signature.borrow());
|
|
let r = self.get_ty(instantiated);
|
|
let r = r.as_ref();
|
|
let signature;
|
|
if let TypeEnum::TFunc(s) = &*r {
|
|
signature = s;
|
|
} else {
|
|
unreachable!();
|
|
}
|
|
// we check to make sure that all required arguments (those without default
|
|
// arguments) are provided, and do not provide the same argument twice.
|
|
let mut required = required.clone();
|
|
let mut all_names: Vec<_> = signature
|
|
.borrow()
|
|
.args
|
|
.iter()
|
|
.map(|v| (v.name, v.ty))
|
|
.rev()
|
|
.collect();
|
|
for (i, t) in posargs.iter().enumerate() {
|
|
if signature.borrow().args.len() <= i {
|
|
return Err("Too many arguments.".to_string());
|
|
}
|
|
if !required.is_empty() {
|
|
required.pop();
|
|
}
|
|
self.unify(all_names.pop().unwrap().1, *t)?;
|
|
}
|
|
for (k, t) in kwargs.iter() {
|
|
if let Some(i) = required.iter().position(|v| v == k) {
|
|
required.remove(i);
|
|
}
|
|
let i = all_names
|
|
.iter()
|
|
.position(|v| &v.0 == k)
|
|
.ok_or_else(|| format!("Unknown keyword argument {}", k))?;
|
|
self.unify(all_names.remove(i).1, *t)?;
|
|
}
|
|
if !required.is_empty() {
|
|
return Err("Expected more arguments".to_string());
|
|
}
|
|
self.unify(*ret, signature.borrow().ret)?;
|
|
*fun.borrow_mut() = Some(instantiated);
|
|
}
|
|
self.set_a_to_b(a, b);
|
|
}
|
|
(TFunc(sign1), TFunc(sign2)) => {
|
|
let (sign1, sign2) = (&*sign1.borrow(), &*sign2.borrow());
|
|
if !sign1.vars.is_empty() || !sign2.vars.is_empty() {
|
|
return Err("Polymorphic function pointer is prohibited.".to_string());
|
|
}
|
|
if sign1.args.len() != sign2.args.len() {
|
|
return Err("Functions differ in number of parameters.".to_string());
|
|
}
|
|
for (x, y) in sign1.args.iter().zip(sign2.args.iter()) {
|
|
if x.name != y.name {
|
|
return Err("Functions differ in parameter names.".to_string());
|
|
}
|
|
if x.default_value != y.default_value {
|
|
return Err("Functions differ in optional parameters value".to_string());
|
|
}
|
|
self.unify(x.ty, y.ty)?;
|
|
}
|
|
self.unify(sign1.ret, sign2.ret)?;
|
|
self.set_a_to_b(a, b);
|
|
}
|
|
_ => {
|
|
if swapped {
|
|
return self.incompatible_types(a, b);
|
|
} else {
|
|
self.unify_impl(b, a, true)?;
|
|
}
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn internal_stringify(&mut self, ty: Type) -> String {
|
|
let top_level = self.top_level.clone();
|
|
self.stringify(
|
|
ty,
|
|
&mut |id| {
|
|
top_level.as_ref().map_or_else(
|
|
|| format!("{}", id),
|
|
|top_level| {
|
|
if let TopLevelDef::Class { name, .. } =
|
|
&*top_level.definitions.read()[id].read()
|
|
{
|
|
name.to_string()
|
|
} else {
|
|
unreachable!("expected class definition")
|
|
}
|
|
},
|
|
)
|
|
},
|
|
&mut |id| format!("var{}", id),
|
|
)
|
|
}
|
|
|
|
/// Get string representation of the type
|
|
pub fn stringify<F, G>(&mut self, ty: Type, obj_to_name: &mut F, var_to_name: &mut G) -> String
|
|
where
|
|
F: FnMut(usize) -> String,
|
|
G: FnMut(u32) -> String,
|
|
{
|
|
use TypeVarMeta::*;
|
|
let ty = self.unification_table.probe_value(ty).clone();
|
|
match ty.as_ref() {
|
|
TypeEnum::TRigidVar { id } => var_to_name(*id),
|
|
TypeEnum::TVar { id, meta: Generic, .. } => var_to_name(*id),
|
|
TypeEnum::TVar { meta: Sequence(map), .. } => {
|
|
let fields = map
|
|
.borrow()
|
|
.iter()
|
|
.map(|(k, v)| format!("{}={}", k, self.stringify(*v, obj_to_name, var_to_name)))
|
|
.join(", ");
|
|
format!("seq[{}]", fields)
|
|
}
|
|
TypeEnum::TVar { meta: Record(fields), .. } => {
|
|
let fields = fields
|
|
.borrow()
|
|
.iter()
|
|
.map(|(k, v)| format!("{}={}", k, self.stringify(*v, obj_to_name, var_to_name)))
|
|
.join(", ");
|
|
format!("record[{}]", fields)
|
|
}
|
|
TypeEnum::TTuple { ty } => {
|
|
let mut fields = ty.iter().map(|v| self.stringify(*v, obj_to_name, var_to_name));
|
|
format!("tuple[{}]", fields.join(", "))
|
|
}
|
|
TypeEnum::TList { ty } => {
|
|
format!("list[{}]", self.stringify(*ty, obj_to_name, var_to_name))
|
|
}
|
|
TypeEnum::TVirtual { ty } => {
|
|
format!("virtual[{}]", self.stringify(*ty, obj_to_name, var_to_name))
|
|
}
|
|
TypeEnum::TObj { obj_id, params, .. } => {
|
|
let name = obj_to_name(obj_id.0);
|
|
let params = params.borrow();
|
|
if !params.is_empty() {
|
|
let params = params.iter().map(|(id, v)| {
|
|
format!("{}->{}", *id, self.stringify(*v, obj_to_name, var_to_name))
|
|
});
|
|
// sort to preserve order
|
|
let mut params = params.sorted();
|
|
format!("{}[{}]", name, params.join(", "))
|
|
} else {
|
|
name
|
|
}
|
|
}
|
|
TypeEnum::TCall { .. } => "call".to_owned(),
|
|
TypeEnum::TFunc(signature) => {
|
|
let params = signature
|
|
.borrow()
|
|
.args
|
|
.iter()
|
|
.map(|arg| {
|
|
format!("{}={}", arg.name, self.stringify(arg.ty, obj_to_name, var_to_name))
|
|
})
|
|
.join(", ");
|
|
let ret = self.stringify(signature.borrow().ret, obj_to_name, var_to_name);
|
|
format!("fn[[{}], {}]", params, ret)
|
|
}
|
|
}
|
|
}
|
|
|
|
fn set_a_to_b(&mut self, a: Type, b: Type) {
|
|
// unify a and b together, and set the value to b's value.
|
|
let table = &mut self.unification_table;
|
|
let ty_b = table.probe_value(b).clone();
|
|
table.unify(a, b);
|
|
table.set_value(a, ty_b)
|
|
}
|
|
|
|
fn incompatible_types(&mut self, a: Type, b: Type) -> Result<(), String> {
|
|
Err(format!(
|
|
"Cannot unify {} with {}",
|
|
self.internal_stringify(a),
|
|
self.internal_stringify(b)
|
|
))
|
|
}
|
|
|
|
/// Instantiate a function if it hasn't been instantiated.
|
|
/// Returns Some(T) where T is the instantiated type.
|
|
/// Returns None if the function is already instantiated.
|
|
fn instantiate_fun(&mut self, ty: Type, fun: &FunSignature) -> Type {
|
|
let mut instantiated = false;
|
|
let mut vars = Vec::new();
|
|
for (k, v) in fun.vars.iter() {
|
|
if let TypeEnum::TVar { id, range, .. } =
|
|
self.unification_table.probe_value(*v).as_ref()
|
|
{
|
|
if k != id {
|
|
instantiated = true;
|
|
break;
|
|
}
|
|
// actually, if the first check succeeded, the function should be uninstatiated.
|
|
// The cloned values must be used and would not be wasted.
|
|
vars.push((*k, range.clone()));
|
|
} else {
|
|
instantiated = true;
|
|
break;
|
|
}
|
|
}
|
|
if instantiated {
|
|
ty
|
|
} else {
|
|
let mapping = vars
|
|
.into_iter()
|
|
.map(|(k, range)| (k, self.get_fresh_var_with_range(range.borrow().as_ref()).0))
|
|
.collect();
|
|
self.subst(ty, &mapping).unwrap_or(ty)
|
|
}
|
|
}
|
|
|
|
/// Substitute type variables within a type into other types.
|
|
/// If this returns Some(T), T would be the substituted type.
|
|
/// If this returns None, the result type would be the original type
|
|
/// (no substitution has to be done).
|
|
pub fn subst(&mut self, a: Type, mapping: &VarMap) -> Option<Type> {
|
|
self.subst_impl(a, mapping, &mut HashMap::new())
|
|
}
|
|
|
|
fn subst_impl(
|
|
&mut self,
|
|
a: Type,
|
|
mapping: &VarMap,
|
|
cache: &mut HashMap<Type, Option<Type>>,
|
|
) -> Option<Type> {
|
|
use TypeVarMeta::*;
|
|
let cached = cache.get_mut(&a);
|
|
if let Some(cached) = cached {
|
|
if cached.is_none() {
|
|
*cached = Some(self.get_fresh_var().0);
|
|
}
|
|
return *cached;
|
|
}
|
|
|
|
let ty = self.unification_table.probe_value(a).clone();
|
|
// this function would only be called when we instantiate functions.
|
|
// function type signature should ONLY contain concrete types and type
|
|
// variables, i.e. things like TRecord, TCall should not occur, and we
|
|
// should be safe to not implement the substitution for those variants.
|
|
match &*ty {
|
|
TypeEnum::TRigidVar { .. } => None,
|
|
TypeEnum::TVar { id, meta: Generic, .. } => mapping.get(&id).cloned(),
|
|
TypeEnum::TTuple { ty } => {
|
|
let mut new_ty = Cow::from(ty);
|
|
for (i, t) in ty.iter().enumerate() {
|
|
if let Some(t1) = self.subst_impl(*t, mapping, cache) {
|
|
new_ty.to_mut()[i] = t1;
|
|
}
|
|
}
|
|
if matches!(new_ty, Cow::Owned(_)) {
|
|
Some(self.add_ty(TypeEnum::TTuple { ty: new_ty.into_owned() }))
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
TypeEnum::TList { ty } => {
|
|
self.subst_impl(*ty, mapping, cache).map(|t| self.add_ty(TypeEnum::TList { ty: t }))
|
|
}
|
|
TypeEnum::TVirtual { ty } => self
|
|
.subst_impl(*ty, mapping, cache)
|
|
.map(|t| self.add_ty(TypeEnum::TVirtual { ty: t })),
|
|
TypeEnum::TObj { obj_id, fields, params } => {
|
|
// Type variables in field types must be present in the type parameter.
|
|
// If the mapping does not contain any type variables in the
|
|
// parameter list, we don't need to substitute the fields.
|
|
// This is also used to prevent infinite substitution...
|
|
let params = params.borrow();
|
|
let need_subst = params.values().any(|v| {
|
|
let ty = self.unification_table.probe_value(*v);
|
|
if let TypeEnum::TVar { id, .. } = ty.as_ref() {
|
|
mapping.contains_key(&id)
|
|
} else {
|
|
false
|
|
}
|
|
});
|
|
if need_subst {
|
|
cache.insert(a, None);
|
|
let obj_id = *obj_id;
|
|
let params =
|
|
self.subst_map(¶ms, mapping, cache).unwrap_or_else(|| params.clone());
|
|
let fields = self
|
|
.subst_map(&fields.borrow(), mapping, cache)
|
|
.unwrap_or_else(|| fields.borrow().clone());
|
|
let new_ty = self.add_ty(TypeEnum::TObj {
|
|
obj_id,
|
|
params: params.into(),
|
|
fields: fields.into(),
|
|
});
|
|
if let Some(var) = cache.get(&a).unwrap() {
|
|
self.unify(new_ty, *var).unwrap();
|
|
}
|
|
Some(new_ty)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
TypeEnum::TFunc(sig) => {
|
|
let FunSignature { args, ret, vars: params } = &*sig.borrow();
|
|
let new_params = self.subst_map(params, mapping, cache);
|
|
let new_ret = self.subst_impl(*ret, mapping, cache);
|
|
let mut new_args = Cow::from(args);
|
|
for (i, t) in args.iter().enumerate() {
|
|
if let Some(t1) = self.subst_impl(t.ty, mapping, cache) {
|
|
let mut t = t.clone();
|
|
t.ty = t1;
|
|
new_args.to_mut()[i] = t;
|
|
}
|
|
}
|
|
if new_params.is_some() || new_ret.is_some() || matches!(new_args, Cow::Owned(..)) {
|
|
let params = new_params.unwrap_or_else(|| params.clone());
|
|
let ret = new_ret.unwrap_or_else(|| *ret);
|
|
let args = new_args.into_owned();
|
|
Some(
|
|
self.add_ty(TypeEnum::TFunc(
|
|
FunSignature { args, ret, vars: params }.into(),
|
|
)),
|
|
)
|
|
} else {
|
|
None
|
|
}
|
|
}
|
|
_ => unimplemented!(),
|
|
}
|
|
}
|
|
|
|
fn subst_map<K>(
|
|
&mut self,
|
|
map: &Mapping<K>,
|
|
mapping: &VarMap,
|
|
cache: &mut HashMap<Type, Option<Type>>,
|
|
) -> Option<Mapping<K>>
|
|
where
|
|
K: std::hash::Hash + std::cmp::Eq + std::clone::Clone,
|
|
{
|
|
let mut map2 = None;
|
|
for (k, v) in map.iter() {
|
|
if let Some(v1) = self.subst_impl(*v, mapping, cache) {
|
|
if map2.is_none() {
|
|
map2 = Some(map.clone());
|
|
}
|
|
*map2.as_mut().unwrap().get_mut(k).unwrap() = v1;
|
|
}
|
|
}
|
|
map2
|
|
}
|
|
|
|
fn occur_check(&mut self, a: Type, b: Type) -> Result<(), String> {
|
|
use TypeVarMeta::*;
|
|
if self.unification_table.unioned(a, b) {
|
|
return Err("Recursive type is prohibited.".to_owned());
|
|
}
|
|
let ty = self.unification_table.probe_value(b).clone();
|
|
|
|
match ty.as_ref() {
|
|
TypeEnum::TRigidVar { .. } | TypeEnum::TVar { meta: Generic, .. } => {}
|
|
TypeEnum::TVar { meta: Sequence(map), .. } => {
|
|
for t in map.borrow().values() {
|
|
self.occur_check(a, *t)?;
|
|
}
|
|
}
|
|
TypeEnum::TVar { meta: Record(map), .. } => {
|
|
for t in map.borrow().values() {
|
|
self.occur_check(a, *t)?;
|
|
}
|
|
}
|
|
TypeEnum::TCall(calls) => {
|
|
let call_store = self.calls.clone();
|
|
for t in calls
|
|
.borrow()
|
|
.iter()
|
|
.map(|call| {
|
|
let call = call_store[call.0].as_ref();
|
|
chain!(call.posargs.iter(), call.kwargs.values(), once(&call.ret))
|
|
})
|
|
.flatten()
|
|
{
|
|
self.occur_check(a, *t)?;
|
|
}
|
|
}
|
|
TypeEnum::TTuple { ty } => {
|
|
for t in ty.iter() {
|
|
self.occur_check(a, *t)?;
|
|
}
|
|
}
|
|
TypeEnum::TList { ty } | TypeEnum::TVirtual { ty } => {
|
|
self.occur_check(a, *ty)?;
|
|
}
|
|
TypeEnum::TObj { params: map, .. } => {
|
|
for t in map.borrow().values() {
|
|
self.occur_check(a, *t)?;
|
|
}
|
|
}
|
|
TypeEnum::TFunc(sig) => {
|
|
let FunSignature { args, ret, vars: params } = &*sig.borrow();
|
|
for t in chain!(args.iter().map(|v| &v.ty), params.values(), once(ret)) {
|
|
self.occur_check(a, *t)?;
|
|
}
|
|
}
|
|
}
|
|
Ok(())
|
|
}
|
|
|
|
fn get_intersection(&mut self, a: Type, b: Type) -> Result<Option<Type>, ()> {
|
|
use TypeEnum::*;
|
|
let x = self.get_ty(a);
|
|
let y = self.get_ty(b);
|
|
match (x.as_ref(), y.as_ref()) {
|
|
(TVar { range: range1, .. }, TVar { meta, range: range2, .. }) => {
|
|
// we should restrict range2
|
|
let range1 = range1.borrow();
|
|
// new range is the intersection of them
|
|
// empty range indicates no constraint
|
|
if !range1.is_empty() {
|
|
let range2 = range2.borrow();
|
|
let mut range = Vec::new();
|
|
if range2.is_empty() {
|
|
range.extend_from_slice(&range1);
|
|
}
|
|
for v1 in range2.iter() {
|
|
for v2 in range1.iter() {
|
|
let result = self.get_intersection(*v1, *v2);
|
|
if let Ok(result) = result {
|
|
range.push(result.unwrap_or(*v2));
|
|
}
|
|
}
|
|
}
|
|
if range.is_empty() {
|
|
Err(())
|
|
} else {
|
|
let id = self.var_id + 1;
|
|
self.var_id += 1;
|
|
let ty = TVar { id, meta: meta.clone(), range: range.into() };
|
|
Ok(Some(self.unification_table.new_key(ty.into())))
|
|
}
|
|
} else {
|
|
Ok(Some(b))
|
|
}
|
|
}
|
|
(_, TVar { range, .. }) => {
|
|
// range should be restricted to the left hand side
|
|
let range = range.borrow();
|
|
if range.is_empty() {
|
|
Ok(Some(a))
|
|
} else {
|
|
for v in range.iter() {
|
|
let result = self.get_intersection(a, *v);
|
|
if let Ok(result) = result {
|
|
return Ok(result.or(Some(a)));
|
|
}
|
|
}
|
|
Err(())
|
|
}
|
|
}
|
|
(TVar { id, range, .. }, _) => {
|
|
self.check_var_compatibility(*id, b, &range.borrow()).or(Err(()))
|
|
}
|
|
(TTuple { ty: ty1 }, TTuple { ty: ty2 }) => {
|
|
if ty1.len() != ty2.len() {
|
|
return Err(());
|
|
}
|
|
let mut need_new = false;
|
|
let mut ty = ty1.clone();
|
|
for (a, b) in zip(ty1.iter(), ty2.iter()) {
|
|
let result = self.get_intersection(*a, *b)?;
|
|
ty.push(result.unwrap_or(*a));
|
|
if result.is_some() {
|
|
need_new = true;
|
|
}
|
|
}
|
|
if need_new {
|
|
Ok(Some(self.add_ty(TTuple { ty })))
|
|
} else {
|
|
Ok(None)
|
|
}
|
|
}
|
|
(TList { ty: ty1 }, TList { ty: ty2 }) => {
|
|
Ok(self.get_intersection(*ty1, *ty2)?.map(|ty| self.add_ty(TList { ty })))
|
|
}
|
|
(TVirtual { ty: ty1 }, TVirtual { ty: ty2 }) => {
|
|
Ok(self.get_intersection(*ty1, *ty2)?.map(|ty| self.add_ty(TVirtual { ty })))
|
|
}
|
|
(TObj { obj_id: id1, .. }, TObj { obj_id: id2, .. }) => {
|
|
if id1 == id2 {
|
|
Ok(None)
|
|
} else {
|
|
Err(())
|
|
}
|
|
}
|
|
// don't deal with function shape for now
|
|
_ => Err(()),
|
|
}
|
|
}
|
|
|
|
fn check_var_compatibility(
|
|
&mut self,
|
|
id: u32,
|
|
b: Type,
|
|
range: &[Type],
|
|
) -> Result<Option<Type>, String> {
|
|
if range.is_empty() {
|
|
return Ok(None);
|
|
}
|
|
for t in range.iter() {
|
|
let result = self.get_intersection(*t, b);
|
|
if let Ok(result) = result {
|
|
return Ok(result);
|
|
}
|
|
}
|
|
return Err(format!(
|
|
"Cannot unify variable {} with {} due to incompatible value range",
|
|
id,
|
|
self.internal_stringify(b)
|
|
));
|
|
}
|
|
}
|